On Forteiland in IJmuiden — a fort from 1881 that is part of the UNESCO Stelling van Amsterdam — event bureau PBN runs two escape experiences that you can only reach by boat ('De Fortwachter'); the crossing itself is part of the story. In 'Het Von Braun Mysterie' you unravel a mystery in an authentic German WWII bunker where rocket scientist Von Braun supposedly worked, while 'The Great Escape' is marketed as 'the largest escape room in the Netherlands': you roam for up to four hours through the underground tunnel system of the island. Everything is sold as a premium evening experience with a guided tour, drinks and a five-course shared dinner in the fort — no hourly puzzle sessions to book separately. Public reviews of the puzzles themselves are scarce; visitors particularly praise the boat crossing, the raw bunkers and dining on the island, with steep group prices (around €99-170 per person all-in).